Paper napkins are formed with forming machines comprising a pair of folding rollers with vertical axes forming a throat through which is fed a paper strip material which is normally folded along a longitudinal line. A system of clamps or suction holes associated with the folding rollers grips the strip material alternately on one side and on the other, so that it is folded in a zigzag configuration after the throat of the rollers. In this way a horizontal stack of folded strip material is formed, and this is pressed against a central blade which cuts the stack into two symmetrical parts, creating two parallel stacks of napkins. The two stacks have to be divided into packs or groups, each containing a predetermined number of napkins. Various separating devices have been designed for this purpose.
In one type of folder, the separation between consecutive packs of napkins is carried out by disposing the napkins in a saw-tooth configuration and inserting separating fingers-between adjacent packs to achieve their separation and discharge. Examples of machines of this type are described in U.S. Pat. No. 3,451,521, DE-A-2,427,635 and U.S. Pat. No. 5,281,082.
In other types of machine, the napkins leave the machine, forming a uniform stack. The two folding rollers of the forming machine are associated with two continuous conveyors disposed on both sides of the channel for the to advance of the stack of material leaving the folder, these conveyors carrying a plurality of separating fingers which are inserted between successive packs of napkins. Each pair of fingers is disposed in a waiting position behind the folding rollers or in a recessed housing in one of the rollers, and when the desired number of napkins has been reached the separating fingers are made to advance with the folded product to the discharge area. A device of this type is described in JP-A-55 7165 A separator which is similar, but which is combined with a machine which feeds previously cut flat sheets, is described in FR-A-2 398 007. In this device, the separating fingers are temporarily released from the continuous conveyor, represented by a chain, and remain housed in a recessed housing of the roller feeding the flat articles. When the desired number of flat articles has been reached, the fingers are engaged with the conveyor and begin to advance in the same direction as the stack of sheets leaving the machine.
A similar system is described in U.S. Pat. No. 4,938,465. Here the separating fingers are engaged with or disengaged from the continuous conveyor by means of a complex magnetic system. In the napkin discharge area, the separating fingers guide a pick-up jaw which grips the individual packs of napkins from above and removes them.
The systems known at the present time are complex and expensive.